Wireshark-users: Re: [Wireshark-users] Jitter wrong in wireshark?
From: Lars Ruoff <[email protected]>
Date: Mon, 26 Feb 2007 14:46:11 +0100
Hi Anders,
since this too is a recurring question, perhaps you (or someone else) could add it to the Wiki, just under what i added last week: http://wiki.wireshark.org/RTP_statistics (bottom).
(I'm sorry, i don't have the time right now).

br,
Lars


Anders Broman wrote:
Hi,
Looking at the sources there is code there to use different frequencies
But for dynamic payload types there are two prerequisites that must be met:
- The setup signalling must be in the traces for Wireshark to track the
PT to the media type.
- The media type sampling frequency must be in the table of rtp_analysis.c

This types are currently specified:
static const mimetype_and_clock mimetype_and_clock_map[] = {
	{"AMR",		8000},  /* [RFC3267] */
	{"AMR-WB",	16000},  /* [RFC3267] */
	{"EVRC",	8000},  /* [RFC3558] */
	{"EVRC0",	8000},  /* [RFC3558] */
	{"G7221",	16000},  /* [RFC3047] */
	{"G726-16",	8000},  /* [RFC3551] */
	{"G726-24",	8000},  /* [RFC3551] */
	{"G726-32",	8000},  /* [RFC3551] */
	{"G726-40",	8000},  /* [RFC3551] */
	{"G729D",	8000},  /* [RFC3551] */
	{"G729E",	8000},  /* [RFC3551] */
	{"GSM-EFR",	8000},  /* [RFC3551] */
	{"mpa-robust",	90000},  /* [RFC3119] */
	{"SMV",		8000},  /* [RFC3558] */
	{"SMV0",	8000},  /* [RFC3558] */
	{"red",		1000},  /* [RFC4102] */
	{"t140",		1000},  /* [RFC4103] */
	{"BMPEG",	90000},  /* [RFC2343],[RFC3555] */
	{"BT656",	90000},  /* [RFC2431],[RFC3555] */
	{"DV",		90000},  /* [RFC3189] */
	{"H263-1998",	90000},  /* [RFC2429],[RFC3555] */
	{"H263-2000",	90000},  /* [RFC2429],[RFC3555] */
	{"MP1S",	90000},  /* [RFC2250],[RFC3555] */
	{"MP2P",	90000},  /* [RFC2250],[RFC3555] */
	{"MP4V-ES",	90000},  /* [RFC3016] */
	{"pointer",	90000},  /* [RFC2862] */
	{"raw",		90000},  /* [RFC4175] */
};
Best regards
Anders



-----Ursprungligt meddelande-----
Från: [email protected]
[mailto:[email protected]] För [email protected]
Skickat: den 24 februari 2007 17:45
Till: [email protected]
Ämne: Re: [Wireshark-users] Jitter wrong in wireshark?

Hi Anders,

Yes, your are right. Codecs affect jitter calculation because of the
sampling frequency. In practice, it affects when calculating the timestamp
to seconds. I.e: when multipling timestamp ticks to convert to seconds one
must use the frequency sampling of the current codec. As wireshark uses
always 0.000125 (it looks like this is not configurable), then if codec is
not G711 calculations will be wrong.
And that´s my case :(
BR
Juan






-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of ext Anders Broman
Sent: Sábado, 24 de Febrero de 2007 04:50 a.m.
To: 'Community support list for Wireshark'
Subject: Re: [Wireshark-users] Jitter wrong in wireshark?

Hi,
If I understood the previous discussion correctly the RTP timestamp which is based on the sampling frequency is used in the calculations. If the wrong sampling frequency is used the calculations will be off.
If a dynamic PT is used (>95) it probably not G711.
Best regards
Anders

________________________________________
Från: [email protected]
[mailto:[email protected]] För [email protected]
Skickat: den 23 februari 2007 18:29
Till: [email protected]
Ämne: Re: [Wireshark-users] Jitter wrong in wireshark?

Hi Anders,
good question. I´m not sure but I guess is codec is PCMA G711 8KHz (will take a look during call setup in a couple of hours). However "Payload type" is 97 (0x61), and wireshark shows it as "Payload type=Unknown" According to the formula, jitter calculation depends on timestamps and arrival time differences. I don´t know how codec could affect. BR
Juan
________________________________________
From: [email protected]
[mailto:[email protected]] On Behalf Of ext Anders Broman (AL/EAB)
Sent: Viernes, 23 de Febrero de 2007 01:05 p.m.
To: Community support list for Wireshark
Subject: SV: [Wireshark-users] Jitter wrong in wireshark?
Hi,
Which codec is used?
Best regards
Anders

________________________________________
Från: [email protected] genom [email protected]
Skickat: fr 2007-02-23 16:53
Till: [email protected]
Ämne: [Wireshark-users] Jitter wrong in wireshark?
Hi All,
Below is a rtp analysis from a wireshark 0.99.5 capture in a live network. Doing by hand jitter calculation it doesn´t match. And of course, if below data is real it means we are having jitter of more than 1 minute !!
Exampe: first jitter should be 138.90/16 = 8.68125 [ms] and is showing
8803,82 [ms] !!! Do someone know what could be wrong or what I´m missing? BR Juan Forward Packet Sequence Delta (ms) Jitter (ms) IP BW (kbps) Marker Status Date Length
1       0       0.00    0.00    1.45            [ Ok ]  02/19/2007
18:44:25.915 231
2       1       138.90  8803.82 2.90            [ Ok ]  02/19/2007
18:44:26.053 231
3 2 119.59 17058.61 4.34 [ Ok ] 02/19/2007
18:44:26.173 231
4 3 139.67 24796.21 5.79 [ Ok ] 02/19/2007
18:44:26.313 231
5 4 180.22 32047.69 7.24 [ Ok ] 02/19/2007
18:44:26.493 231
6 5 241.67 38842.10 8.69 [ Ok ] 02/19/2007
18:44:26.735 231
7 6 96.71 45220.93 10.14 [ Ok ] 02/19/2007
18:44:26.831 231
8 7 198.41 51194.72 10.14 [ Ok ] 02/19/2007 18:44:27.030 231 9 8 205.78 56794.69 8.69 [ Ok ] 02/19/2007
18:44:27.235 231
10 9 193.62 62045.42 8.69 [ Ok ] 02/19/2007
18:44:27.429 231
11 10 197.77 66967.72 8.69 [ Ok ] 02/19/2007
18:44:27.627 231
12 11 208.31 71581.72 7.24 [ Ok ] 02/19/2007
18:44:27.835 231
13 12 190.92 75908.43 8.69 [ Ok ] 02/19/2007
18:44:28.026 231
14 13 199.23 79964.20 8.69 [ Ok ] 02/19/2007
18:44:28.225 231
15 14 183.31 83767.48 8.69 [ Ok ] 02/19/2007
18:44:28.409 231
16 15 200.50 87331.98 8.69 [ Ok ] 02/19/2007
18:44:28.609 231
17 16 216.07 90672.73 8.69 [ Ok ] 02/19/2007
18:44:28.825 231
18 17 137.81 93809.57 8.69 [ Ok ] 02/19/2007
18:44:28.963 231
19 18 139.08 96750.28 8.69 [ Ok ] 02/19/2007
18:44:29.102 231
20 19 119.60 99508.41 10.14 [ Ok ] 02/19/2007
18:44:29.222 231
21 20 119.59 102094.16 10.14 [ Ok ] 02/19/2007
18:44:29.341 231
22 21 119.18 104518.33 10.14 [ Ok ] 02/19/2007 18:44:29.460 231 23 22 126.80 106790.51 11.58 [ Ok ] 02/19/2007
18:44:29.587 231
24 23 112.05 108921.60 11.58 [ Ok ] 02/19/2007
18:44:29.699 231
25 24 145.14 110917.43 11.58 [ Ok ] 02/19/2007
18:44:29.844 231
26 25 115.57 112790.36 13.03 [ Ok ] 02/19/2007 18:44:29.960 231 27 26 118.57 114546.05 13.03 [ Ok ] 02/19/2007
18:44:30.079 231
28 27 139.44 116190.71 13.03 [ Ok ] 02/19/2007
18:44:30.218 231
29 28 120.40 117733.77 13.03 [ Ok ] 02/19/2007
18:44:30.338 231
30 29 118.59 119180.49 13.03 [ Ok ] 02/19/2007
18:44:30.457 231
31 30 120.00 120536.71 13.03 [ Ok ] 02/19/2007
18:44:30.577 231
32 31 120.23 121808.15 13.03 [ Ok ] 02/19/2007
18:44:30.697 231
33 32 119.60 123000.17 13.03 [ Ok ] 02/19/2007
18:44:30.817 231
34 33 118.72 124117.74 13.03 [ Ok ] 02/19/2007
18:44:30.936 231
35 34 119.88 125165.39 13.03 [ Ok ] 02/19/2007
18:44:31.055 231
36 35 146.42 126145.90 13.03 [ Ok ] 02/19/2007
18:44:31.202 231
37 36 57.34 118265.37 11.90 SET Incorrect timestamp 02/19/2007 18:44:31.259 90 Reverse Packet Sequence Delta (ms) Jitter (ms) IP BW (kbps) Marker Status Date Length
44      1       0.00    0.00    1.45            [ Ok ]  02/19/2007
18:44:36.119 231
46 2 126.78 99992.08 2.90 [ Ok ] 02/19/2007
18:44:36.246 231
47 3 293.16 193724.25 4.34 [ Ok ] 02/19/2007
18:44:36.539 231
48 4 159.97 281606.49 5.79 [ Ok ] 02/19/2007
18:44:36.699 231
49 5 119.98 363998.58 7.24 [ Ok ] 02/19/2007
18:44:36.819 231
50 6 160.07 441238.67 8.69 [ Ok ] 02/19/2007
18:44:36.979 231
51 7 261.00 513644.94 8.69 [ Ok ] 02/19/2007 18:44:37.240 231 52 8 43.09 481544.82 7.56 SET Incorrect timestamp 02/19/2007 18:44:37.283 90 _______________________________________________
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